Beech's AT-11 Kansan was another military derivation of the company's Model 18 "Twin Beech" transport, in this case intended for the training of bomber gunners and bombardiers. The airframe had a clear nose installed, in addition to bomb bays. Most had a dorsal turret with two .30-cal machine guns and a single handheld gun position, while initial production aircraft had a single turret gun. Some three dozen examples were converted to AT-11A navigator trainers.
AT-11 Bibliography:
Beechcraft ad, showing an AT-11 on the ground with engines running Aviation December 1941
Warbirds International May 2000 Side view of AT-11 N501 as rebuilt with portside skydiver's door